#include <string>
#include <fstream>
#include <iostream>
#include "../Utility.h"

using namespace std;

int main(int argc, char const *argv[])
{
  Timer t;
  
  ifstream ifs("breedflip.in");
  ofstream ofs("breedflip.out");

  int n; // The number of cows
  string a, b;
  ifs >> n >> a >> b;

  int times = 0;
  bool mismatch = false;

  for (int i = 0; i < a.size(); ++i) {
    if (a[i] != b[i]) {
      if (!mismatch) {
        mismatch = true;
        ++times;
      }
    }
    else {
      mismatch = false;
    }
  }

  ofs<<times;
  return 0;
}

